1. Field of the Invention
The present invention relates to a deck drain replacement assembly for use in marine applications.
2. Description of Related Art
Drains are commonly found on the decks of military ships, to allow standing water and other liquids to drain from the surface of the deck. Such drains are generally provided with a drain strainer which spans the opening of the drain, and which is mounted substantially flush with the deck, so as to avoid the presence of protrusions or recesses on the surface of the deck. The drain strainer is commonly a disc having a pattern of perforations or other openings which permit liquid and small particles to pass therethrough, while presenting a physical barrier precluding larger objects from entering the drain. The drain strainer also provides continuity to the deck surface.
On U.S. military ships, a common deck drain construction (see FIG. 1) involves the provision of a drain basket 10, a peripheral flange 12 of which is secured flush with the deck surface DS, with the basket having a drain opening 14 of a predetermined size or diameter. In this known design, a plurality, usually three or four, lugs 16 are provided to extend radially inwardly from an inner surface 18 of the drain basket 10. Each of the lugs 16 has a substantially flat upper surface, and the collective upper surfaces substantially define a common plane located at a predetermined distance below the surface of the deck DS.
Each lug 16 is tapped to receive a retaining screw or bolt therein. A drain strainer 20 made of a solid disk of metal, and having the perforations or openings therein, is sized to reasonably closely fit the diameter of the opening defined by the drain basket 10. The drain strainer 20 is also of a thickness substantially equal to the distance at which the lugs 16 are recessed below the deck surface DS. Being sized in that manner, the drain strainer 20 will be received in drain basket 10, and the upper surface 21 of the drain strainer will lie substantially flush with the deck surface 100.
For the sake of complete accuracy, it is to be noted that the load bearing deck on the ship is usually coated with an approximately ½″ thick deck covering, such as a terrazzo material or ceramic tile. The term “deck surface” as used herein will refer to the exposed surface, whether that be the steel load bearing elements, or the deck covering, where such a covering is employed. In the drawings, the deck is represented as a single layer, for purposes of simplicity.
The drain strainer 18 has a plurality of tapped or untapped bores 22 through which screw or bolt fasteners 24 can be introduced. The bores 22 are produced in the drain strainer 18 to align with the bores on lugs 16. The drain strainer is thus secured to the drain basket 10 by the plurality of fasteners 24.
This design is initially generally satisfactory. However, once the ship or craft has been put into service, it has proven to be difficult to maintain the drains in their original operating condition. A significant problem with the above design is that the fasteners (screws) corrode and strip out, thereby leaving the drain strainer 20 either unsecured or only partially secured, leading to potentially dangerous situations.
It is possible to replace an entire drain assembly, including the drain basket 10, however, this is a fairly costly endeavor, and the lead time for procuring the assembly can be extensive. Further, this replacement process, which involves welding or otherwise securing the flange of the drain basket to the deck, may not be suitable under the then prevailing conditions.
An attempt to address this problem has previously been proposed. A drain strainer repair kit has been developed and used, albeit with only limited success. The repair or replacement under this approach involves chiseling off, grinding off, or sawing off the lugs 16. It is to be noted, in this respect, that broken or malfunctioning lugs are also common in this shipboard environment. Once the lugs have been removed, a cylindrical brass ring insert 30 (FIG. 2), having an outer diameter substantially equal to the diameter of the opening in drain basket 10, is inserted into the drain basket.
It can be seen in FIG. 2 that, at the level at which the lugs 16 were previously provided, the wall thickness of the drain basket 10 increases in thickness, thereby leaving a small “step” 11 in the wall of the drain basket at that level. The brass ring insert 30 is sized to closely conform to the stepped-in wall section of the drain basket. The brass ring insert 30 is of sufficient thickness that bores 32 spanning the step 11 and the insert 30 can be produced once the insert is in place.
In this design, the brass ring insert 30 is intended to be lowered into and positioned within drain basket 10 such that an upper surface 31 thereof is positioned at the same level as the step 11, i.e., at the level at which the upper surfaces of lugs 16 were previously present. Once so positioned, a plurality of set screws or socket screws 34 are tightened through horizontal bores 36 extending through the wall of insert 30, into contact with the inner wall of drain basket 10, to retain the insert at this position.
A plurality of tapped bores 38 must then be produced at the juncture of the brass ring insert and stepped-in portion of the drain basket wall. In order to facilitate proper positioning of these bores, the drain strainer is usually placed in its operative position atop the insert, and the bores are then created through the openings in the drain strainer. The drain strainer is then secured in position by fasteners 24 (see FIG. 1).
This repair modification has significant drawbacks. It has proven to be fairly difficult to properly position brass ring insert 30 such that the upper surface of the insert is flush with the upper surface of step 11 of the drain basket. Often, the ring is slightly or significantly skewed or cocked, which results in the drain strainer that seats on the upper surface of the insert also being skewed or cocked, thus causing part of the drain strainer to either protrude above the level of the deck surface DS or to be recessed below the deck surface. In either case, a potentially dangerous situation is presented.
In addition, the requirement to create the tapped bores in situ adds considerable complexity to the process, particularly if the repair is to be conducted at sea. Furthermore, the bore is created an area at which two different elements made of two different materials abut against each other. This further complicates the process and can lead to an improper repair being performed. The drilling and tapping of the bores is also very time consuming, and shipboard personnel have thus, in many instances, opted to not perform the repair at sea, and instead allow the unsatisfactory situation to remain until the repair can be effected when the ship returns to port.
An attempted improvement on the above repair procedure has been proposed. In that proposal, a replacement drain strainer having fastener holes moved closer to center is provided, thus permitting the fastener retaining bores to be drilled and tapped only into the brass ring insert 3a. This proposed solution does not, however, eliminate the need to perform in situ drilling and tapping, nor does it address the problem of properly positioning and aligning the insert 30 in the drain basket 10.
It is therefore a principal object of the present invention to provide a repair/replacement assembly for marine deck drains which overcomes the aforenoted disadvantages.